Charge forming device



CHARGE FORMING DEVICE Filed Sept. 20, 1928 2 Sheets-Sheet 1 fnvenfar' JMM,MMVM

Sept. 5, 1933. F. E. ASELTINE CHARGE FORMING DEVICE Filed Sept. 20, 1928 2 Sheets-Sheet 2 JEJ 5.

firs l'fbme 5 Patented Sept. 5, 1933 UNITED STATES PATENT OFFICE CHARGE FORMING DEVICE Application September 20, 1928 Serial No. 307,243

15 Claims.

This invention relates to charge forming devices for internal combustion engines and more particularly to the type of charge forming device which comprises a plurality of primary fuel mixing chambers, one for each intake port of the engine, which cooperate respectively with a plurality of secondary mixing chambers located adjacent the said intake ports and receiving primary mixture from pipes connected with the primary carburetors while receiving air, when required, through the branches of an air manifold having a single air inlet for admitting air to all of said secondary mixing chambers. A single fuel reservoir supplies liquid fuel to all of said primary mixing chambers.

Examples of charge forming devices of this character are disclosed in the copending applications of Wilford H. Teeter. Serial No. 221,372, filed September 22, 1927 which matured to Patent 1,819,526 issued Aug. 18, 1931, and Fred E. Aseltine and Wilford H. Teeter, Serial No. 221,371, filed September 22, 1927 which matured to Patent 1,819,495 issued Aug. 18, 1931.

In prior devices of this type, such as those disclosed in the above mentioned copending applications,varlous means are provided to regulate the proportions of fuel and air in the mixture under different operating conditions, so as to provide a mixture having the desired proportions to most satisfactorily operate the engine under all conditions of speed and load. One of these mixture proportioning devices is a spring held air valve adapted to regulate the admission of air to the carburetor and provided with a dash pot to retard the opening of said valve on opening movements of the throttle to temporarily restrict the admission of air in order to provide a mixture rich enough to properly operate the engine during the acceleration period. Under certain operating conditions when the throttle is oper. .d at relatively high speeds, the effect of the dash pot in retarding .he opening of the air valve is such that the suction at the fuel Jets is temporarily increased sufllciently to form too rich a mixture. resulting in unsteady operation and possible stalling of the engine, until the air valve is moved to fully open position as determined by the throttle position at completion of its opening movement. This action might occur for instance. when the vehicle 60 on which the device is used is coasting at a speed of 30 miles per hour or more with closed throttle, and the throttle is suddenly opened. At the vehicular speed mentioned. the manifold suction is high and on opening of the throttle this high suction is communicated to the air valve and to the fuel jets. Because of the action of the dash pot in resisting the opening of said air valve, the suction at the jets becomes temporarily too great, resulting in sumcient flow of fuel therefrom to form too rich a mixture, and causing erratic operation of the engine until the resistance of the dash pot is overcome.

It is accordingly the principal object of the present invention to provide means for preventing the mixture becoming too rich on opening movement of the throttle under any operating conditlons. More specifically, it is an object of the present invention to automatically restrict the fuel supply passage on opening movements of the throttle at relatively high vehicular speeds. It is a further object of the invention to provide a dash pot for retarding the opening of the valve regulating the air supply and to provide means compensating for the effect of the dash pot under certain operating conditions whereby the formation of a too rich mixture is prevented.

These objects are accomplished according to the present invention by providing a fuel supply passage in addition to the main fuel supply passage, which is controlled by a valve operated by a diaphragm which is subject to the suction in the mixture passage and constructed so as to close the valve as the throttle is opened, to regulate the supply of fuel to the mixing chambers in the manner fully described hereinafter.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal section on line 1-1 of Fig. 6 through a. charge forming device in which a preferred form of the present invention is embodied.

Fig. 2 is a vertical transverse section on the line 22 of F18. 6.

Figs. 3 and 4 are side elevations of the carburetor unit looked at from opposite sides.

Fig. 5 is a detail elevation of the primary throttle.

Fig. 6 is a horizontal section on the line 6-6 of Fig. 2.

The device disclosed comprises a main air manimm 10 having three outlet branches, the middle branch 12 being shown herein. Each of these branches communicates with one of the intake ports 14 of a multicylinder engine. These outlet branches are each provided with an attaching flange 16 for securing the manifold to the engine block in the usual manner. Adjacent the inlet of the manifold is provided a flange 18 to which the main carburetor unit is adapted to be attached, as shown in Fig. 1.

The carburetor unit comprises a main housing 20, having an attaching flange 22 adapted to be secured to flange 18 by screws 24. An air inlet hom 28 is secured in position to register with an opening in the upper wall of housing 20, in any suitable way. A casting 30, having certain dash pot chambers and fuel passages formed therein, is secured by screws to the lower wall of housing 20, and a sheet metal fuel bowl 32 is held tight against an annular shoulder 34 on the housing by any suitable means. Fuel is conducted from a main source of supply to the fuel bowl through a conduit not shown herein and the flow of fuel to the bowl is controlled by a float 36, operating in the usual manner to maintain a substantially constant level of fuel therein.

Fuel flows from bowl 32 to a plurality of primary fuel nozzles 38, one of which is located in each of the primary mixing chambers 40, the construction of which is briefly described hereinafter. The fuel conduit between the fuel bowl and the nozzles comprises a vertical fuel passage 42 communicating at its upper end with a horizontal fuel canal 44 which connects with each of the nozzles 38 through orifices 46.

Fuel is normally admitted to the passage 42 from the fuel bowl through a fixed mixing orifice 48 and for acceleration is also admitted to said passage 42 through orifice 50, controlled by a valve 52 in the manner set forth hereinafter.

Fuel is lifted from the fuel bowl through the above described fuel passages and nozzles 38 to the mixing chambers by the suction therein. Closing movements of the throttle cause a reduction in mixing chamber suction which might permit the fuel column to drop sufllciently to cause a temporary fuel starving of the engine unless means were provided to prevent it. For this purpose a check valve 54 is provided in an enlarged chamber 56 at the junction of chambers 42 and 44 and on reduction of mixing chamber suction seats on a rib projecting upwardly from the bottom of the chamber 56 as shown in Fig. 2, preventing downward flow of fuel. A two stage metering valve 57 of the type shown in the earlier applications above referred to controls the flow of fuel through the passage 42 in the manner set forth in said applications.

Each primary fuel nozzle is provided with a main fuel outlet 58 in the top of the nozzle and a secondary fuel outlet comprising two orifices 60 and 62 near the bottom of the vertical wall of the nozzle. At relatively high speeds, the mixing chamber suction is enough to lift fuel from the main outlet as well as from holes 60 and 62. At idle or low speeds, however, the suction is sufficient to lift fuel only to some point between the top of the nozzle and orifices 60 and 62, fuel fiow ing from these orifices by action of gravity. Each nozzle is provided with a restricted fuel metering orifice 63. The primary mixture passages 38 are parallel to each other and close together, as indicated in Fig. 2, and when the carburetor is attached to the manifold, these passages register with conduits which convey the primary mixture to the secondary mixing chambers, as fully disclosed in the copending applications referred to.

A single throttle valve 64, which extends across all the primary mixture passages, controls the flow therethrough and is provided with grooves 66 which register with said mixture passages.

This throttle is operated by means fully disclosed in the above copending applications and which forms no part of the present invention. The middle primary mixture passage connects with a tube 68, fixed in the manifold branch 12, which conveys the primary mixture to the secondary mixing chamber in that branch of the manifold.

The throttle is provided with a groove 69 which cooperates with a screw 69a to prevent any longitudinal movement of said throttle.

Substantially all the air entering the carburetoi fiows through the air horn 28, controlled by a main air valve 70, normally held against a seat 72, by a spring '14, received between the valve and a flange 76 projecting from a sleeve 78 slidably mounted on a stationary guide sleeve 80, fixed in the housing 20, and serving as a guide sleeve for the stem 82 to which the air valve is secured.

When it is desired to choke the carburetor to facilitate starting of the engine, the flange is adapted to be lifted by an arm 83, in the manner set forth in the above mentioned applications, until the upper end of the sleeve engages the valve to hold it against its seat. Sufiicient air to carry the starting fuel from the nozzles to the intake ports is admitted through an elongated slot 84, formed in a plate 86, secured to the housing 20, as shown in Fig. 1.

The valve 70 admits air to amain air chamber 88 from which air flows to the primary mixture passages through an orifice 90 in the floor of the air chamber and to the secondary mixing chambers through an air passage'92, controlled by a manually operable throttle 94, secured to a shaft 96, and operated concurrently with the primary throttle by a common operating mechanism, which is fully described in the above mentioned applications and forms no part of this invention.

On opening of either or both of the throttles, suction in the air chamber is increased and the air valve is opened against the tension of its spring to admit additional air. The opening of this valve is retarded to some extent, however, to enrich the mixture for purposes of acceleration and to prevent fluttering of said valve by means of a liquid dash pot. This dash pot comprises a cylinder 100, located within the fuel bowl 32, and cooperating with a piston 102, secured in any desirable manner to the lower end of the air valve stem 82. This dash pot constitutes no part of the present invention and maybe of any desired construction, such for instance as that shown in the copending application Serial No. 288,683 filed June 2'7, 1928.

When the throttle is opened, under certain operating conditioniilas indicated hereinbefore, the dash pot in retarding the opening of the air valve causes a suction to be built up at the jets which is suflicient to effect too great a flow of fuel to form a mixture of proper proportions, but instead forms a mixture rich enough to cause the engine to run unevenly until the air valve opens against the action of the dash pot. It is the purpose of the present invention to provide means to prevent the formation of too rich a mixture when the throttle is opened rapidly at relatively high vehicular speeds for acceleration or for any other purpose. To this end means are provided to automatically reduce the effective area of the fuel supply passage on opening movements of the throttle such as above described whenever the suction effective-on the fuel jets reaches a predetermined degree. This means comprises the fuel valve 52 which is controlled by the suction in chamber 88 and is operated to fully or partially close the fuel inlet 50. To this endthe valve 52 is pivotally connected to one end of a lever 110 pivoted on a pin 112 projecting from the main housing 20. The lever is connected at its opposite end to a link 114, connected to a diaphragm 116 which closes a cup shaped mem her 118 to form a suction chamber. The member 118 is secured to a suction pipe 120 in any desirable manner which will provide a leak proof joint between said member and the suction pipe. The

pipe 120 extends through the wall of the housing so as to communicate with the chamber 88 and positioned between the diaphragm 116 and the chamber 118. is a helical spring 122 surrounding the end of the pipe 120 which projects into the suction chamber and operating to hold the fuel valve 52 in wide open position when permitted to do so by the engine suction.

The above described means for operating the valve 52 operates substantially as follows:

When the engine is not running atmospheric pressure is maintained on both sides of the diaphragm 116 and the spring 122 is effective to hold the diaphragm in the position shown in Fig. 3 with fuel valve 52 fully open. Since the suction connection 120 communicates with the main air chamber which is anterior to the throttle, the suction effective on the diaphragm 116 at idling or low speed operation under load is very little so that the valve 52 remains fully open, the strength of the spring 122 being such that the valve is never moved toward closed position at any speed less than a vehicular speed of miles per hour. However, when the throttle is opened at speeds above 30 miles per hour either from a closed position, as when the vehicle is coasting, or from a partially open position to a more fully open position for purposes of acceleration, the high manifold suction is communicated to the chamber 88 and owing to resistance presented by the dash pot to the opening of the air valve, the suction in such chamber, which is effective on thediaphragm 116; becomes great enough temporarily to partially or wholly collapse the spring 122, partially or wholly closing the valve 52. The movement of the valve will depend on the operating conditions and the movement of the throttle, the greater the speed and the greater the manifold suction which is communicated to the chamber 88, the greater the movement of the valve. After the resistance of the dash pot is overcome and the valve reaches its open position, as determined by the position of the throttle, the suction in the chamber 88 drops and the valve returns toward its open position depending on the speed and throttle position.

If the throttle is opened from a closed position, as when coasting, to a relatively wide open position, the suction effective on the diaphragm is suillcient to collapse the spring 122 entirely and fully close the valve 52 preventing any enrichment of the mixture. The reason for this is that the vehicle being already moving at relatively high speed no enrichment of the mixture is necessary to speed up the engine. Also if running down hill with the throttle closed and clutch engaged and the throttle is suddenly opened, the action is the same, no enrichment of the mixture being desirable when the engine is already running at high speed. If, however, the throttle is opened when operating under load at speeds above 30 miles per hour, the fuel valve 52 is partially closed and the degree of closing is greater the wider the throttle is opened. This reduces the area of the fuel supply passage as the suction effective at the jets is increased, thus tending to keep the supply of accelerating fuel provided on opening of the throttle to accelerate at different speeds substantially uniform.

The throttle operating mechanism, while constituting no part of the present invention, will now be briefly described to enable a general understanding of the whole device without reference to other disclosures. Fixed on aspindle 130, projecting from the primary throttle and integral therewith, is an operating arm 132 having a hole in its free end adapted to be connected to some suitable form of operating connection extending to a point convenient to the operator of the vehicle. This operating arm is connected through a lost motion connection to an arm 134 clamped by screw 136 to the end of shaft 96 outside the housing 20. The lost motion connection comprises an operating link 138 pivotally connected to arm 132 and provided with a slot 140 through which projects a pin 142, secured to the arm 134. A regulating screw 144 is threaded 1n lugs 146. projecting from link 138, and may be adjusted to regulate the effective length of the slot 140, the upper end of screw 144 constituting one end of said slot. A tension spring 148 is connected to the upper end of link 138 and pin 142, tending to hold the pin against the upper end of slot 140. With both throttles closed, the parts are in the position shown in Fig. 4, with the pin 142 in engagement with screw 144. As the operating arm 132 is rotated in a counter-clockwise direction to open the primary throttle valve, the link 138 is moved downwardly until the upper end of slot 140 strikes pin 142 before the arm 134 is moved, in order to partly open the primary throttle before the throttle 94 begins to open. The screw 144 serves as a stop to limit the closing movement of the primary throttle and adjustment of said screw regulates the opening of the primary throttle for idling.

There are three secondary mixing chambers, one associated with each branch of the manifold, and one of such mixing chambers is shown herein. Each. of these mixing chambers comprises a Venturi tube 150 clamped between the manifold and the engine block and positioned so that the outlet of the primary mixture conduit associated therewith terminates at the point of greatest sucion therein. These Venturi tubes constitute no part of the present invention, but function in the manner fully set forth in the above mentioned copending applications.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A charge forming device for multicylinder internal combustion engines comprising a plurality of secondary mixing chambers, a plurality of primary mixing chambers delivering fuel mixture thereto, fuel andair inlets therefor, and an air chamber supplying air to all of said mixing chambers, a throttle, means for supplying additional fuel to said primary mixing chambers on opening movements of said throttle, and means for controlling the effectiveness of the fuel supply means in accordance with the suction in said air chamber.

2. A charge forming device for internal combustion engines comprising, a mixture passage, fuel and air inlets therefor. a throttle, a fuel passage supplying said fuel inlet, means operable on opening movements of the throttle to cause additional fuel to be supplied to the mixture passage for enriching the mixture during the acceleration period, a valve controlling the admission of fuel to said fuel passage, suction operated means for variably positioning the valve to regulate the action of the mixture enriching means, and a suction connection extending from said means to the mixture passage at a point anterior to the throttle.

3. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, means operable on opening movements of the throttle for enriching the mixture during the acceleration period, and means for rendering the enriching means less effective as the throttle is opened.

4. A charge forming device for internal combustion engines comprising a mixture passage. fuel and air inlets therefor, means operable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, and means for rendering the mixture enriching means less effective as the suction in the mixture passage anterior to the throttle is increased.

5. A charge forming device for internal combustion engines comprising, a mixture passage, fuel and air inlets therefor, means ope able on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, and suction operated means for rendering the mixture enriching means less efiective as the throttle is opened to more fully open positions.

6. Acharge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage during the acceleration period to enrich the mixture, and means operable on opening movements of the throttle under certain operating conditions to reduce the amount of fuel supplied to the mixture passage, whereby the mixture enriching means is rendered substantially ineffective.

7. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage during the acceleration period to enrich the mixture, and means operable on opening movements of the throttle at relatively high speeds under certain operating conditions to reduce the amount of fuel supplied to the mixture passage, whereby the mixture enriching means is rendered substantially ineffective.

8. A charge forming device for internal combustion engines, comprising a mixture passage, fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle under all operating conditions at speeds below a certain predetermined speed and under certain conditions at speeds above said predetermined speed, for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, and means operable on opening movements of the throttle under certain operating conditions for reducing the amount of fuel delivered to the mixture e, Y

whereby the mixture enriching means is rendered wholly or partially ineffective.

9. A charge forming device for internal combustion engines, comprising a mixture passage, fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle under all operating conditions at speeds below a certain predetermined speed and under certain 'conditions at speeds above said predetermined speed, for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, and suction operated means operable on opening movements of the throttle under certain operating conditions for reducing the amount of fuel delivered to the mixture passage, whereby the mixture enriching means is rendered wholly or partially ineflective.

10. A charge forming device for internal combustion engines, comprising a mixture passage,

fuel and air inlets therefor, athrottle, means operable on opening movements of the throttle under all operating conditions at speeds below a certain predetermined speed and under certain conditions at speeds above said predetermined speed, for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, and means operable on opening movements of the throttle at speeds above said predetermined speed under certain operating conditions for reducing the amount of fuel delivered to the mixture passage, whereby the mixture enriching means is rendered wholly or partly ineffective.

11. A charge forming device for internal combustion engines, comprising a mixture passage, fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, means for regulating the effectiveness of the mixture enriching means, said last named means comprising a normally unrestricted fuel port, and means for wholly or partly restricting said fuel port on opening movements of the throttle under certain operating conditions.

12. A charge forming device for internal combustion engines, comprising a mixture passage, fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, means for regulating the effectiveness of the mixture enriching means, said last named means comprising a normally unrestricted fuel port, a valve for wholly or partly restricting said fuel port, a diaphragm connected to said valve, and means for communicating the suction of the mixture passage to said diaphragm.

13. A charge forming device for internal com bustion engines, comprising a mixture passage, fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, means for regulating the effectiveness of the mixture enriching means, said last named means comprising a normally unrestricted fuel port, a valve for wholly or partly restricting said fuel port, a diaphragm connected to said valve, and a suction connection extending from the diaphragm to the mixture passage at a point anterior to the throttle.

14. A charge forming device for internal combustion engines, comprising a mixture passage,

fuel and air inlets therefor, a throttle, means operable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, means for regulating the effectiveness of the mixture enriching means, said last named means comprising a normally unrestricted fuel port, a valve for wholly or partly restricting said fuel port, a diaphragm connected erable on opening movements of the throttle for increasing the amount of fuel supplied to the mixture passage to enrich the mixture during the acceleration period, means for regulating the effectiveness of the mixture enriching means, said last named means comprising a normally unrestricted fuel port, a valve for wholly or partly restricting said fuel port, a diaphragm connected to said valve, a spring adapted to engage the diaphragm to hold the valve open and means to communicate the suction oi the mixture passage to the diaphragm to overcome the force of said spring and move the valve toward closed position under certain operating conditions, said spring being of suflicient strength to hold the valve open at all engine speeds below that corresponding to a vehicular speed of substantially thirty miles per hour on a level.

FRED E. ASELTINE. 

